1. Field of the Invention
The present invention relates to a printed circuit board having an insulating support layer and a layer of conductive material applied thereto.
2. Description of Related Art
Printed circuit boards of the type cited at the outset are known from the prior art as “rigid printed circuit boards”. They are used for mechanically mounting electronic components (resistors, capacitors, coils, integrated circuits (ICs), etc.) and for making electrical contact with said components. To this end, connecting lines (conductor tracks) are produced from the thin layer of conductive material by means of mask etching, for example. The components are usually soldered onto solder areas (“pads”) or into holes and solder eyes (surrounding the holes) and in this way are mechanically mounted and have electrical contact made with them at the same time. However, other methods for mounting and/or making contact with the components on the printed circuit board are known, such as bonding, clamping or welding.
Conventional rigid printed circuit boards usually comprise an electrically insulating support material (base material) to which a copper layer has been applied. The layer thickness is typically 35 μm, and for applications with relatively high current levels it is between 70 μm and 140 μm. Previously, the base material used was frequently Pertinax (phenolic resin with paper fibers, “hard paper”, material identifier FR2). Today, fiberglass mats soaked in epoxy resin are usually used (material identifier FR4). This material has better resistance to leakage currents and better radiofrequency properties and also lower water absorption than hard paper. For special applications, other materials are also used, such as Teflon or ceramic in LTCC or HTCC for radiofrequency technology or glass. For printed circuit boards with high demands on heat dissipation, base materials with metal cores are used, e.g. in the field of lighting technology for high-power LEDs.
A drawback of the known rigid printed circuit boards is the low flexibility thereof in terms of their shape. For this reason, known controllers are usually in the form of rectangular boxes, the bases of which have the rigid printed circuit board running on them. Shapes other than a rectangular shape for the controllers would make no sense, since the shape of said controllers would not be able to be filled efficiently by the known rigid printed circuit boards.
In addition, the prior art discloses flexible printed circuit boards, in which the insulating support layer comprises a film, for example of polyester, polyethylene naphthalate (PEN) or polyimide (PI). Flexible printed circuit boards have the advantage that their shape can also adapt to more complex shapes of controller housings, i.e. the interior of controllers can be used particularly efficiently. However, the flexible printed circuit boards have the drawback that their contours need to be punched. This is relatively complex and is suitable only for relatively large numbers of items on account of the relatively high tool and machine costs. Furthermore, the flexible printed circuit boards need to be held and/or fixed in their shape that is put into the controller, since they otherwise readopt their original shape on account of the flexibility of the support layer. In addition, the flexible printed circuit boards are not as robust as rigid printed circuit boards and can tear, for example. Finally, the flexible printed circuit boards are also relatively expensive.
In addition, the prior art discloses “rigid-flexible” printed circuit boards, which are a combination of flexible and rigid printed circuit boards. The connections comprise flexible runs which are nondetachably connected to the rigid portions of the printed circuit board. The rigid regions serve as a solid base for holding electrical components and connectors. The flexible connections can be used to determine and vary the position of the rigid portions supporting components. Rigid-flexible printed circuit boards are very complex to produce and therefore also very expensive, however.